Semiconductor manufacturing involves various processes, such as mounting a plurality of semiconductor dice to a substrate, forming electrical connections between the dice and the substrate, encapsulating the dice and substrate with a plastic encapsulating material, such as epoxy resin, and separating each molded electronic component from one another to form individual semiconductor packages.
The electronic components are encapsulated using a molding process. During this process, the substrate is introduced into a mold cavity formed by two mold halves. The substrate is sandwiched between the mold halves with the semiconductor dice positioned in corresponding cavities of the mold. Encapsulating material is introduced into the cavities and is allowed to set and harden. The mold halves are then opened, the encapsulating material is allowed to cure, and the cull and other unwanted encapsulating material are then removed in a degating process.
Conventionally, the mold halves are designed to accommodate and mold all the plurality of semiconductor dice on a substrate at the same time. Whilst this conventional method is a simple molding method, and has been used for many years, there are several disadvantages associated with its use. Since mold chases comprised in the mold halves have larger areas to accommodate an entire array of semiconductor dice on the substrate, they require larger presses and higher clamping tonnage to secure the molding areas and provide a better sealing effect to prevent encapsulating material from leaking during the molding process. Also, since there are more semiconductor dice to be molded in one molding cycle, it requires a more complex mold chase design comprising runners and mold cavities to properly channel the encapsulating material to each die position for effective molding. The use of the mold chase may be more expensive because a new mold chase design would be required to cater to each substrate length and width. Even if the basic patterns of the dice arrangements are the same, a new mold chase would be necessary for, say, a longer length of substrate. All these factors lead to increased costs in the implementations of conventional molding systems.
Prior art molding systems also require pick-and-place transfer mechanisms for substrates, pre-heaters before molding and curing ovens after molding. This involves more complexity in operation and generally higher equipment cost to support the molding operation. Further, each molding shot to mold a whole substrate normally consumes seven to eight epoxy resin pellets. A fast pellet preparation turnaround time is therefore required.